Cucumis L.
Cucumis L., Sp. Pl. 1011. 1753.
Type: Cucumis sativus L., Herb. Burser XVII: 97 (UPS), lectotype.
Melo Mill., Gard. Dict. Abr. ed. 4. 1754.
Hymenosicyos Chiov. Ann. Bot. (Rome) 9: 62. 1911.
Cucumella Chiov., Fl. Somala 1: 183. 1929.
Dicoelospermum C. B. Clarke in J. D. Hooker, Fl. Brit. India 2: 605, 630. 1879. (‚Dicaelospermum‚, correction Post & Kuntze. 1903 (‚1904‘).
Mukia Arn. in R. Wight, Madras J. Lit. Sci. 12: 50. 1840.
Myrmecosicyos C. Jeffrey, Kew Bull. 15: 357. 1962.
Oreosyce Hook. in Oliv., Fl. Trop. Africa 2: 548. 1871.

Small to medium-sized annual or short-lived perennial herbs or woody climbers and trailers with fibrous roots or perennial rootstock (rarely tubers) and monoecious or less often dioecious sex system. The leaves are simple with unlobed or palmately lobed blade, petiolate. The tendrils are simple, usually solitary, rarely in groups of 5-8 or absent. Male and female flowers are solitary or in few-flowered groups, small to medium-sized. The receptacle-tube is funnel-shaped to campanulate or shallowly saucer-shaped. The five sepals are small, long-triangular to filiform, the five petals are yellow, elliptic or (ob)ovate, free or united at base. The three stamens are inserted halfway up the tube on short, glabrous filaments short. Two anthers are bithecous, one monothecous with lateral, straight (sometimes apically hooked) or triplicate thecae, rarely thecae horizontal, arcuate and slightly coherent (C. messorius). The pollen is small to medium-sized (polar axis 22-61 µm, equatorial axis 49-80 µm), tricolporate, tri(poro)porate, (micro)reticulate-perforate (Khunwasi 1998). The ovary is hairy, globose to oblong with several horizontal ovules. The style is terete, thick, glabrous with an entire, sublobate or trilobed stigma and carnose stigmatic lobes, often with 1-9 finger-like projections on the margin. The fruit is solitary or in clusters of 2-6, fleshy, (sub)globose or ellipsoid, cylindrical, (ob)ovoid, or spindle-shaped, smooth and glabrous or pubescent or with dense to scattered fleshy spines, pustules or tubercles, sometimes beaked or fusiform, ripening yellow, orange, red or greenish to brownish, often with longitudinal pale stripes (rarely maturing underground), indehiscent (rarely expelling seeds explosively). The seeds are ovate or elliptic, small to medium-sized, globose or lenticular compressed with light-coloured testa, smooth or ornamented, glabrous or rarely puberulent, margin often distinct, usually not winged. The chromosome numbers are n = 7 or 12, with polyploids and aneuploids also reported (Beevy and Kuriachan 1996).

The 65 species grow in semi-deserts and savannas, dry bushland and along forest margins, often on disturbed or cultivated ground in Africa, Asia and Australia.

Cucumis is sister group to Muellerargia from Madagascar and Australia and both group with Coccinia in recent phylogeny estimates (Schaefer et al. 2009; Schaefer & Renner 2011).

Literature

Beevy, S. S. and P. Kuriachan. 1996. Chromosome numbers of South Indian Cucurbitaceae and a note on the cytological evolution in the family. J. Cytol. Genet. 31: 65-71.

De Wilde, W. J. J. O. and B. E. E. Duyfjes. 2007. Mukia Arn. (Cucurbitaceae) in Asia, in particular in Thailand. Thai Forest Bull., Bot. 34: 38-52.

Endl, J., Achigan-Dako, E., Pandey, A.K., Montforte, A.J., Pico, B., Schaefer, H. 2018. Repeated domestication of melon (Cucumis melo) in Africa and Asia and a new close relative from India. American Journal of Botany 105: 1-10.

Ghebretinsae, A.G., M. Thulin, and J.C. Barber. 2007. Relationships of cucumbers and melons unraveled: molecular phylogenetics of Cucumis and related genera (Benincaseae, Cucurbitaceae). Amer. J. Bot. 94: 1256-1266.

Jeffrey, C. 1969. The genus Mukia in Asia, Malesia and Australasia. Hooker’s Icon. Pl. 5, 7, 3: 1-12.

Khunwasi, C. 1998. Palynology of the Cucurbitaceae. Doctoral Dissertation Naturwiss. Fak., University of Innsbruck.

Kirkbride, J. H. 1994. Revision of Cucumella (Cucurbitaceae, Cucurbitoideae, Melothrieae, Cucumerinae). Brittonia 46: 161-186.

Naudin, C.V. 1859. Essaie d’une monographie des espèces et des variétés du genre Cucumis. Ann. Sci. Nat., Bot. sér. 4, 11: 5-87.

Renner, S. S., Schaefer, H. and A. Kocyan, A. 2007. Phylogenetics of Cucumis (Cucurbitaceae): Cucumber (C. sativus) belongs in an Australian/ Asian clade far from African melon (C. melo). BMC Evol. Biol. 7: 58.

Schaefer, H. 2007. Cucumis (Cucurbitaceae) must include Cucumella, Dicoelospermum, Mukia, Myrmecosicyos, and Oreosyce: a recircumscription based on nuclear and plastid DNA data. Blumea 52: 165-177.

Schaefer, H. and S.S. Renner. 2011. Phylogenetic relationships in the order Cucurbitales and a new classification of the gourd family (Cucurbitaceae). Taxon 60: 122-138.

Schaefer, H., Heibl, C., and S.S. Renner. 2009. Gourds afloat: a dated phylogeny reveals an Asian origin of the gourd family (Cucurbitaceae) and numerous oversea dispersal events. Proceedings of the Royal Society B 276: 843-851.

Sebastian, P., Schaefer, H., Telford, I.R.H., and S.S. Renner. 2010. Cucumber (Cucumis sativus) and melon (C. melo) have numerous wild relatives in Asia and Australia, and the sister species of melon is from Australia. PNAS 107: 14269-14273.